in which \(\Lambda =\lbrace (i_{1},j_{1}),(i_{2},j_{2}),\dots ,(i_{n},j_{n})\rbrace \)  denotes the set of pixel indices which are selected randomly. We argue that \(\mathcal {L}_{pair}\)  not only keeps the advantages of the gradient loss [1]} which penalizes the adjacent pixels of smooth areas and discontinued borders, but also provides similarity of pixels that are far apart, guaranteeing relative distances of different objects.
